The present invention relates to a head assembly for reading and/or writing information, which has a head slider positioned at a predetermined position with respect to a storage medium, and it also relates to storage devices such as magnetic disk devices (floppy disk devices, hard disk devices, etc.), optical disk devices and tape disk devices.
The conventional storage device is constructed to rotate a disk so that a head slider is caused to float a small distance from the surface of the disk, enabling the head slider to move in the radial direction of the disk. This conventional head slider is generally provided with a head element for recording and/or reading information.
In current information storage devices using magnetooptical disks, the head slider has a magnetic head for reading and/or writing a bias magnetic field to/from the head slider. In addition, an optical head of an objective lens or luminous elements for leading the light to the disk can also be mounted upon the head slider.
Most types of head sliders are supported by suspensions having elasticity which allows for flexing of the head slider towards or away from the disk. The head slider floats a slight distance from the surface of the disk due to the action caused by the air flow generated on the rotating disk surface, i.e., the head floats due to the principles of dynamic air pressure bearings. Higher recording densities and increasing miniaturization are currently being achieved with disk devices, and head sliders are being designed for lower floating heights to achieve miniaturization and lighter weight. However, if the floating height of the slider is designed so that it is too low, the head slider comes into contact with the disk surface due to floating level fluctuations. Such a condition has not been a problem in the past, but eventually, the probability of the slider coming into contact with the disk will be too high, and reliability will reduced because of damage occurring to the head slider and/or the head element parts.
FIG. 1(A) shows a prior art head assembly. The head assembly 20 is generally composed of a head slider 26 and a suspension 21. The suspension 21 is formed by press punching one sheet of an SUS plate, and has an arm attaching surface 23 which is to be attached to an arm of the disk device. The arm attaching surface 23 is formed with an attaching hole 23A, and is furnished with a spacer 23B to ensure that the attaching strength is adequate.
The suspension 21 is also provided with a slider attaching portion 25D for attaching the head slider 26 to the suspension 21 at the opposite end of the arm attaching surface 23. The adhesion surface 26T of the head slider 26 is firmly secured to the suspension 21 by means of an adhesive 22 coated on the slider attaching portion 25D. The slider attaching portion 25D is created by a generally U-shaped hole 25 formed around the perimeter thereof, and the slider attaching portion 25D is supported by three connected beams 25A, 25B, 25C.
The structure of this suspension 21 enables the head slider 26 to be responsive to the air flowing backwards, forwards, to the right, and to the left. However, since the suspension 21 is, as stated above, press-formed, it is often twisted in direction xe2x80x9caxe2x80x9d or in direction xe2x80x9cbxe2x80x9d due to stresses created during forming. The slider attaching portion 25D is, accordingly, affected by the twisting, though the arm attaching surface 23 of the disk device is designed to be positioned so that it is parallel to the disc surface. Furthermore, since the slider attaching portion 25D and the adhesion surface 26T of the head slider are planar, if the head slider 26 is attached to a twisted slider attaching portion 25D, the head slider 26 will be inclined with respect to the disk surface.
In summary, when the slider attaching portion 25D is twisted at an angle of xcex1/2 in direction xe2x80x9caxe2x80x9d with respect to the attaching surface 23, the surface 26D of the head slider 26 facing the disk (in this case the lower surface of the slider) is inclined similar to plane 29A of FIG. 1(A). Thus, because of this inclination, there is a reduction in the floating height of the read/write element 26A (which may be any type of element for reading and/or writing information to/from a disk). Additionally, the frequency of contact of the slider with the disk is also increased. These conditions often result in damage to the head, the suspension and/or the disk.
Conversely, when the slider attaching surface 25D is twisted at an angle of xcex1/2 in direction xe2x80x9cbxe2x80x9d with respect to the attaching surface 23, the surface 26D of the head slider 26 facing the disk is inclined in a manner similar to plane 29B. Thus, the floating height of the read/write element 26A is increased, and the distance between the head and the recording film of the disk is increased so that the recording and/or reading characteristics are degraded.
FIG. 1(B) shows a graph of the floating height of the head slider 20 along different portions of radius of the disk. Line 41 represents the case with no torsion existing in the suspension, and the floating height is constant from the inner side of the disk to the outer side and where the head slider floats at a predetermined height, irrespective of its position on the disk. Line 42 represents the case with torsion existing in the suspension, and where the floating height is reduced going from the inner side of the disk to the outer side, resulting in instability. Since the floating height of the head slider is lower than the designed value, the probability of the head slider coming into contact with the disk is increased. Thus, to secure the floating stability of the head slider, there should be no torsion in the suspension.
Accordingly, in view of the problems discussed above, an objective of the present invention is to provide a head assembly and a storage device which are capable of improving the floating stability of the head slider, as well as improving the reliability of the storage device. It is another objective of the invention to provide a head assembly and a storage device which can provide a highly precise parallel relationship between the surface of the head slider facing a storage medium and the attaching surface of the support plate at the disk device side.
Briefly, with head assembly of the present invention, it is possible to arrange the surface of the head slider facing the disk to be parallel to the disk surface, even if there is some torsion or twisting in the suspension. The effects of torsion can be mitigated against by using a nonplanar or curved portion, on the suspension, for attaching the slider to the suspension. Alternatively, it is also possible to mitigate the effects of torsion by using a nonplanar or curved portion on the surface of the slider where it is attached to the suspension. As an additional alternative, it is also possible to have nonplanar or curved portions on both the suspension and the slider attaching surface. As a result of the nonplanar surface(s), the read/write element will be held at a predetermined distance from the recording film of the disk. Thus, the floating height of the head slider can be held at a constant distance from both the inner and outer sides of the disk. Accordingly, it is possible to enhance the recording and reading efficiency, durability, and reliability of the disk device by reducing the frequency of contact between the head slider and the disk.
More specifically, the present invention relates to a head assembly that includes a head slider with a read/write element for reading/recording information to/from a disk and a suspension for supporting the head slider. The suspension includes a generally planar sheet that extends in a longitudinal direction from a first end to second end and an arm attaching portion located near the first end of the generally planar sheet of said suspension. The arm attaching portion is adapted to be attached to a head arm. The suspension also includes a slider attaching portion positioned near the second end of the generally planar sheet of the suspension, where the slider attaching portion extends generally in the longitudinal direction and is surrounded by a generally U-shaped opening in the generally planar sheet. The slider attaching portion faces a securing surface of the head slider. At least one of the slider attaching portion of the suspension and the securing surface of the head slider includes a nonplanar portion, and the head slider and the suspension are affixed to each other at the nonplanar portion, whereby the effects of torsion upon the alignment of the head slider are mitigated by the nonplanar portion. Preferably, the nonplanar portion includes a curved portion.
The present invention also relates to an information storage device incorporating the above-mentioned head assembly, as well as to the suspension of that head assembly.